Rotary transformer



Oct. 27, 1936. a M PE T R 2,059,024

ROTARY TRANSFORMER Filed June 24, 1933 INYENIOR Giuseppe M. Pestarini ATTORNEY Patented Oct. 27, 1936 UNITED STATES PATENT OFFICE z,o59 ,o24 v ROTARY TRANSFORMER Giuseppe Massimo Pestarini, Sheflield, England Application June 24, 1933, Serial No. 677,521 In Great Britain July 29, 1932 3 Claims. (Cl. 171-123) This invention relates to rotary transformers ated with one commutator and one or both of for direct electric currents and to electric motor the secondary brushes being associated with the equipments operated in connection therewith. other commutator in quadrature electrical rela- More particularly the invention relates to rotary tion to the primary brush set. The two commu- 5 transformers of the type known as and hereintators are connected to a single winding in which 5 after called metadyne transformers which are both the primary and secondary currents circumachines designed to transform a current suplate. As the primary brushes are separated by a plied thereto at a fixed voltage and variable amconsiderable distance from the secondary brushes peres into a current at constant amperes and liability to flash-over between these pairs of variable voltage. A metadyne transformer combrushes is substantially eliminated. If a meta- 10 prises in general a rotor provided with windings dyne transformer is designed as a one-cycle maand a commutator somewhat similar to the archine, that is to say the same disposition of elecmature of a direct current dynamo electric ma trical elements and magnetic elements occurs chine. Four brushes are arranged to make oononly once in progressin thr one complete 5 tact with the commutator, two of which are used turn round the rotor in the air gap between the for the primary circuit and two with the secrotor and stat r. th p m ry a d s d y ondary circuit arranged in quadrature electrical brushes will be located at opposite ends of difrelation with the primary brushes. The rotor is ferent diameters of the machine at right ang es rotated at a constant speed in the magnetic field to c o e t s further eliminating the which is due to the currents circulating in the l ty o fla W a u ye machine 20 rotor windings, a stator being provided which afthe diameters at the respective ends of which the fords a return path of low magnetic resistance pr mary n secondary brushe are located will for the flux which is set up by the rotor currents. n b p pen i ular and the brushes will not be The stator is furnished with windings by which located so far apart as n a y le a hin various magnetic fluxes can be obtained which Otherwise the conditions are similar. The VOlt- 25 combine with the magnetic fluxes due to the prie e we n tw contiguous commutator mary and secondary currents circulating in the ments in a metadyne transformer is furthermore regulator and ther b regulate th l tr less favourable to the occurrence of fiash-overs mechanical performance of the machine. For a than is the Case With an Ordinary y a fuller description of metadyne transformers ref- Chine. u Voltage b w n e s unde 30 erence is directed to the specifications of French s me conditions alls t zero, or may v n be Patents No. 547,855, dated 25th February 1922, v r h mmu rs may b located at No. 623,438, dated 27th January 1926, and No. p s t nd f the machine, or in some cases 637,946, dated 25th November 1926. fl h guards m y be pr vided on each commu- A description of the general construction and 118.130! at the zone Of commutation Of the brushes 35 operation of metadyne transformers, generators of the Other c utator if desired.

and motors treated mathematically in consider- Where the rotor is provided with a single windable detail will also be found in a paper entitled in and two ommu at r th pr m y r sh Essuisse sur la Metadyne by G, M, Pestarim which is connected to the high voltage terminal o in the Bulletin Scientifique A. I. M. No. 4 April of the upp y uit may be associated with one 1931 of lAssociation des Ingnieurs Electriciens, commutator and the other brushes, namely the published by the Institut Electrotechnique other primary br h nd he r h y wh Montefiore, Liege. current is conducted to and from the secondary Motadyne transformers when operated at high circuit, associated with the second commutator,

voltages, 1500 or 3000 volts for example, as comor in some cases one of the secondary brushes monly employed in electric locomotives, are liable may be associated with the same commutator as to serious sparking at the commutator segments that with which the primary brush connected to which may produce flash-overs and arcs from the high voltage te in of t pp is a o brush to brush resulting in damage to the comated. In these cases it is clear that no flash-over mutator and brushes, and the chief object of the from e h h Voltage p y b u h can reach present invention is to provide improved cony p t d e y C n cted to earth.

structions which will avoid this objection. With metadyne transformers having two com- According to the invention a metadynetransmutators as hereinabove described the load or former rotor is provided with two commutators, consumption devi es in the s ondary i uit may i one or both of the primary brushes being associbe arranged across the secondary brushes which are then connected in what is commonly termed a cross-connection. Where, however, the load is such as to be readily divisible into two parts, for example where it comprises a plurality of motors which can be readily divided into two groups, one group may be connected between one primary brush and one secondary brush, and the other group connected between the other primary brush and the remaining secondary brush, this is commonly known as the figure-B connection. When the rotor has only one winding the figure-B connection can only be used if the load is divisible into two substantially similar parts and it is pref erable to employ some series field windings on the motors in order to assist in maintaining stable conditions of the motors.

In order that the invention may be clearly understood it will now be described with reference to the accompanying drawing the figures of which are electrical diagrams illustrating various meth* ods of carrying out the same in practice.

In all the figures the rotor of a metadyne transformer is indicated at l and the stator at 2. The primary brushes are. shown at 3 and 4, respectively connected to a source of current supply indicated by a trolley line T and to ground G, and the secondary brushes are shown at 5 and 5 arranged in quadrature electrical relation to the primary brushes l and 2. The commutators associated with the rotor winding are indicated as two concentric circles of segments 8 and 9. In Figs. 2, 4, and 5 the load in the secondary circuit is indicated as comprising two motors ill, li connected between the primary and secondary brushes in the well known figure-8 connection, and in Figs. 1 and 3 the load, which in Fig. 1 comprises two motors l2 and I3 and in Fig. 3 comprises a single motor I4, is included between the secondary brushes in the well known crossconnection.

In Fig. 1 the rotor l of the metadyne transformer has a single winding indicated at 20, and both the commutators 8 and 9 are connected to said winding. In this figure the motors l2 and I3 are shown as connected between the secondary brushes 5 and 6, and since they are connected in series through the rotor winding 20 it is unnecessary to provide series field windings in the motor circuits.

Referring now to Fig. 2 the metadyne transformer is constructed in a similar manner to that shown in Fig. 1, but the motors in and II forming the load are arranged in figure-B connection. It will be observed that current can flow through each motor independently in a local circuit, for example through the motor Hi, the primary brush 3 and secondary brush 5, which are connected through the rotor winding 2|]. The motors are therefore not strictly connected in series and it is preferable to provide some field windings on the motors.

Referring now to Fig. 3 the rotor I of the. transformer is provided with a winding 20 connected to the two commutators 8 and 9. Only one brush 3 is, however, associated with the commutator 8, the other primary brush 4 being associated with the commutator 9, with which also the secondary brushes 5 and G are associated. The load, indicated as being a motor i4, is in thls'flgure shown in cross connection.

In Fig. 4 the arrangements of the metadyne transformer are similar to those of Fig. 3 but the load is shown as comprising two motors Ill and II which are. connected in figure-8 connection.

In Fig. 5 the rotor l of the transformer is provided with a winding 20, and one primary brush 3 and one secondary brush 5 are shown as being associated with the commutator 8 while the remaining primary brush 4 and secondary brush 6 are associated with the commutator 9. The load in this instance is shown as consisting of two motors l0 and H, of which motor in is connected between the primary brush 3 and the secondary brush 5, the motor ll being connected between the primary brush 4 and the secondary brush 6. The sense of rotation is preferably the one indicated by the arrow (counter-clockwise). With this disposition a flash-over starting from the primary brush-set associated with the high voltage terminal cannot reach any other brush-set unless it makes of a complete revolution which is very improbable.

The fields of the motors in Figure 3 may be separately excited, either with or without series field windings but in the arrangements shown in Figs. 4, and 5 the motors are preferably provided with series field windings as in that shown in Figure 2.

I claim:

1. A rotary transformer having a rotor provided with a primary brush set and a secondary brush set located substantially in quadrature electrical relation with said primary brush set, one

brush only of said primary brush set being associated with one of said commutators and being connected to a source of electrical supply, said other primary brush and said secondary brushes being associated with the other commutator, a load circuit, and means for connecting said load circuit across said secondary brushes.

2. A rotary transformer having a rotor pro vided with a primary brush set and a secondary brush set located substantially in quadrature electrical relation with said primary brush set, one

brush only of said primary brush set being associated with one of said commutators and being connected to a source of electrical supply, said other primary brush and said secondary brushes being associated with the other commutator, a

load circuit, and means for connecting said load circuit across a pair of said brushes including a primary brush and a secondary brush.

3. A rotary transformer having a rotor provided with a winding associated with two commutators, a primary brush set and a secondary brush set electrically displaced from said primary brush set, a high voltage source of electrical power supply, means for connecting one brush of said primary brush set to said high voltage source of power supply, said one brush of said primary brush set being the only brush associated with one commutator, the next following brush in the sense of rotation being associated with the other commutator, and all other brushes being associated with said other commutator.

GIUSEPPE MASSIMO PESTARINI. 

